17. Καὶ οἷσιν ἅπαξ, ἢ δὶς, καὶ πλείω ἢ ἐλάσσω, καὶ κατὰ μέρος· δοτέον δέ τι καὶ τῷ ἔθει, καὶ τῇ ὥρῃ, καὶ τῇ χώρῃ, καὶ τῇ ἡλικίη.